Treatment of petroleum production wells



1956 H. JENKS ETI'AL TREATMENT OF PETROLEUM PRODUCTIONIIYIELLS Filed Ap'ril 29, 1953 PRODUCING WELL BORE METAL BRIDGING PLUG HEATERS, IO0,000 BTU OR LARGER FIG-2 Inventors Loren H. Jenks Ray J. Sfancli 1, Jr.

By I/UI U Attorney TREATMENT OF PETROLEUM PRODUCTION WELLS Loren H. Jenks and Ray J. Stanclift, Jr., Tulsa, Okla., assignors to Esso Research and Engineering Company, a corporation of Delaware Application April 29, 1953, Serial No. 351,924

6 Claims. (Cl. 16639) This invention concerns a novel method and apparatus for increasing the rate of production from petroleum wells. As disclosed and claimed herein, a novel technique is employed for heating the portion of an oil reservoir adjacent a production well so as to decrease the viscosity of infiowing oil and so as to increase production rate and ultimate oil recovery. The heating technique employed utilizes a plurality of heaters set in the vicinity of the production zone of a well so as to heat oil in place in the reservoir in an area surrounding a production well.

In the production of petroleum oil from natural oil reservoirs, a wel lis drilled which penetrates an oil-bearing formation in the earth. By utilization of known production techniques including Well pumping, repressuring, and secondary recover operations, oil is caused to flow from the reservoir into a production well. Production wells may be spaced through the reservoir in a variety of ways and at variable spacings. However, in general, a single production well produces oil from a portion of a reservoir amounting to about 1 to 200 acres. In considering the flow of oil from an oil-bearing formation of the general area identified into a production well, it is apparent that the region immediately surrounding the production well creates a real bottleneck in production. The concentration of flowing oil in this region is far beyond that in the reservoir as a whole. In terms of the pressure drop occuring, a very substantial portion of the pressure drop resulting from flow occurs in the immediate vicinity of the producing well bore.

Appreciating this factor, there have been many suggestion for improving the flow of oil into a production well. For example, it is standard parctice to enlarge the bore hole at the producing formation by under-reaming or the like, so as to reduce the restriction of flow into the borehole. Again it has been suggested to heat the producing formation adjacent a producing well by means of various types of heaters positioned in the producing borehole. The heating methods which have been suggested are characterized by serious disadvantages however. Positioning a heater in a producing well adjacent a producing formation is relatively inefiective in heating the formation or oil at any distance from the borehole. The major portion of the heat is uselessly dissipated in heating oil which has already reached the borehole. It is obviously inefficient to attampt to heat oil in place in the formation by the conductivity of heat contra to the flow of oil into the borehole.

This invention constitutes an improved manner of heating an oil reservoir in the vicinity of a producing well. The invention utilizes recently developed drilling techniques in conjunction with well apparatus which has been developed for other applications. Essentially the technique of this invention resides in the placement of a plurality of heating units in separate boreholes spaced about a producing well. The boreholes may be provided by drilling deviating offshoots from the producing well. Alternatively, in the case of shallow oil fields, boreholes may be drilled from the surface of the earth in the imted States Patent mediate vicinity of a producing well. The heating units employed are preferably electrical heaters of substantial capacity. It is the particular concept of this invention that these heaters should be placed in the auxiliary boreholes referred to in a manner preventing flow of oil past these heaters. In other words, by employing packing arrangements, the heaters are placed in the auxiliary boreholes so that no heat is lost to fluid flowingthrough the boreholes in which the heaters are placed. The formation about the producing oil well is thereby effectively heated by conduction.

As a result of this heating technique the reservoir and oil in place about a producing well can be substantially heated; thereby the viscosity of the crude petroleum oil can be substantially reduced so as to increase the flow rate of this oil through the bottleneck region immediately about the producing well. The result is to greatly increase the efiective area of the producing well so as to substantially increase the rate at which oil can be produced therefrom.

In the accompanying drawing is shown a preferred embodiment of this invention utilizing three deviating boreholes from a central producing well bore. In these drawmgs:

Figure 1 is a plan view of the heating arrangement employed, and I Figure 2 is a cross-sectional elevation view along the line II-II of Figure 1.

It is assumed that a producing well bore identified by the numeral 2 has been drilled into the earth so as to penetrate an oil-bearing formation 3. In accordance with this invention, in order to increase the rate of oil production from borehole 2, a plurality of deviating oflshoots are drilled from borehole 2. These deviating boreholes are identified by numerals 4. Standard technique may be used for drilling the desired number of offshoots. For example, at some level near the top of the producing formation or somewhat above the producing formation, a drill deflector 5 may be positioned. Deflectors of a suitable character that are commercially available may be adapted for use in this invention. For example, directional drilling tools of the character illustrated at page 2278 of the Composite Catalogue of Oil Field and Pipe,- line Equipment, 17th edition, may beemployed. Tools of this character are adapted to be fixed at any position in a well bore to cause deflection of a drill bit so as to permit drilling the required deviating borehole. The deviating offshoots may all be drilled from the same level of the producing well bore as illustrated or if desired the deviating boreholes may be drilled from somewhat different levels of the producing well bore. In any case a number of these auxiliary boreholes are drilled so as to extend from the producing well at a substantial angle in a manner permitting separation of the auxiliary boreholes from the producing well by a distance of about 10 to 50 feet in the producing formation. While any desired number of auxiliary boreholes may be drilled, preferably at least three such auxiliary boreholes are employed.

Thereafter, heating units of the general character illustrated are inserted in each of the auxiilary boreholes. The heating units preferentially constitute lowermost portions identified by numeral 6, which constitute the actual heating elements. For the purposes of this invention it is preferred that the heating elements constitute electrical heaters having a capacity of about 100,000 B. t. us or greater. Immediately above each of the individual heating units is a packing element 7. These packers are adapted to expand in the borehole so as to prevent flow of fluid along the auxiliary boreholes 4. Again suitable packers for use in this invention are known and commercially available. For example, packers of the character illustrated on page 535 of the Com- 'posite Catalogue of Oil Field and Pipeline Equipment;

17th edition, may be employed. .These packers are of thecharacter depending upon an explosive charge to seat the packer in the borehole. 'When the heating units have been placed in the auxiliary boreholes asldescribed and illustrated, the

deviating well plug may be removed. It is convenient to accomplish this by simplydropping the plug to the a bottom of the borehole so that it will not obstruct flow of fluid from the producing formation 3 into the producing well bore 2. Electrical 'current will then be supplied to each of the'electrical heaters and normal production techniques from borehole 2 may then be carried out.

,In the'practical utilization of this'inventionit is convenient in drilling the required auxiliary boreholes to employ an oriented'whipstock. A first ofishoot maybe ing formation in the immediate vicinity of the'producing Well: 7 2. A heating arrangement for a producing well pene- I trating a producing formation comprisingjin combina- 7 tion; at least three boreholes deviating and extending downwardly from said producing well at a substantial drilled with this whipstock oriented in afirst position.

Thereafter, the whipstock may be rotated about 120 in the" borehole and a secondofishoot can be drilled. Finally, the whipstock can be turned another 120 in the borehole and the third ofishoot can be drilled. By similarly ro- V tating thewhipstock as the electrical heating units are lowered into the borehole, these 'unitstwill therefore be directed into each of the auxiliary. boreholes.

' It will be observed'that in the use of this invention,

heat dissipated in the heating elements is necessarily transferred directly into the producing formation in the general vicinity of a producing well. None of this heat is uselessly lost by heating of fluid in the auxiliary well 7 bores, since the packers employed prevent any flow of Asa result the total heat input employed is effective in heating oil in the course of fluid past the heating units;

its fiow to the producing well through the bottleneck region of the producing formation; thereby the rate of oil production from each individual producing Well can be substantially increased with a corresponding improvement in the ultimate oil recovery which can be economically secured. It is apparent that this invention is of application during any stage of production including the socalled ,primaryrecovery and secondary recovery stages. 7

What is claimedis: V t

l. A well production arrangement which includes a plurality of auxiliary boreholes spaced about a producing well which penetrates a producing formatioma heatingunit positioned ineach of said auxiliary boreholes, a packing arrangement positioned Within each 'said auxiliary bore hole immediately above the heating unit and adapted to prevent the flow of fluid pastthe heating unit, each said auxiliary'bore hole being spaced from'the producing wella distance such that heat emitted by the heating-unit in each auxiliary borehole heats the producwell.

angle spaced aboutsa id producing welL a' heating unit of substantial heating capacity positionedin each of said boreholes, a packing element positioned abovefeach of said heating units in each of said boreholes adapted to prevent flow of fluid from said boreholes said'bore holes being spaced from-the producing well a distance such that the heatingunit in each bore hole heats the producing formation in the immediate vicinity of th Producing V 3. The heating arrangement defined ity of auxiliary bore holes abQout the producing well and within the producing formation, introducing heat, into part of the formation from each of'said auxiliary bore holes while preventing flow of -fiuids within the auxiliary bore holes, spacing each auxiliary borehole from the producing well a distance such that the part of the forma tion heated lies in the immediate vicinity of the producing well, and withdrawing oil from the formation through the producing well. a

formation which comprises drilling at least three downwardly inclined bore holes intothe formati'omthe bore holes extending and deviating from the producing well,

sealing each bore hole from the producing well to'pre vent fluid ,flow within the borehole, introducing heat from each bore hole into the formation in the immediate vicinity of'the producing WeILjand WithdraWing oil from.

the formation through the producing well.

6. A method as defined in claim 5 in which each bore 7 hole is extended about 10 to 50 feet within the producing formation.

References Cited in the file of thispatent UNITED. STATES PATENTS 5 Albaugh Aug. 10, 1 954 by claim 2" in Whichthe said heating units constitute electrical heaters;

4. A method for increasing the rate of production of V 7 oil from 'BJ PIOdllClflg well that penetrates a producing formation which comprises drilling and spacing a plural- 5. A method for increasing the rate of production of oil from a producing well that penetrates a producing Gardner j Feb. 14,1905 

